Can i make 500 hp and still have a smooth idle?

[Back N Black]

I have a 440 that i'm rebuilding very soon.This is what i have collected so far. Edelbrock RPM Heads, Edelbrock RPM intake, Holly 770 street avenger carb, Carter mechanical fuel pump. The rear has a 323 gear and a 727 trans. Not sure on the Cam? The car will be used as a cruiser and maybe take it down the track on occasion. I would like to jump in the car, one pump on the gas and fire right up .

[mauve66]

as a side note a friend of mine had a 440 6pak in a green 69 sweptline truck and he never had to pump the gas to start it, he'd just reach in through the window and turn the key, fired up everytime, i've never been able to get any of my carb cars to do that, and he thought it was funny that i couldn't

[375instroke]

Usually one needs to pump the gas at least once to seat the choke and fast idle.  Wonder if his carb was dumping raw gas out the venturies?

[aifilaw]

I have a 440 that i'm rebuilding very soon.This is what i have collected so far. Edelbrock RPM Heads, Edelbrock RPM intake, Holly 770 street avenger carb, Carter mechanical fuel pump. The rear has a 323 gear and a 727 trans. Not sure on the Cam? The car will be used as a cruiser and maybe take it down the track on occasion. I would like to jump in the car, one pump on the gas and fire right up .

First.... throw away the 770 street avenger carb idea. Get a 750 double pumper, you will thank me. If you are dead set on it, I've got an 870 street avenger I would LOVE to sell you, because I only hang out with smart people around here, and none of them are crazy enough to trade for my mistake I made 7 years ago that's still in perfect condition.

To get back to your question.... highly doubtful
The cam is kind of what chooses whether you have a smooth idle, and getting a car to make good power means positioning the operating RPM of the cam in a place to make more power. Stock cars have smooth idles because the cams are positioned to make the best power from 2000-3000 RPM, hence they make great power there, and idle is close enough so that it doesn't behave erratically there.
Performance cams are meant for other ranges, and because horsepower is a function of torque, which means your best numbers will be after 5252 RPM, then picking a cam for 3000-5000 RPM operation range would be more suitable, which means your idle will not be smooth because it is outside of the camshafts operating range.

But, there is hope. Obviously because I have seen many cars that put down 500+ HP numbers with pretty smooth idles. How do they do it? Bigger cubes (stroke the 440), or forced induction, (supercharge or turbocharge it)

[Back N Black]

I have a 440 that i'm rebuilding very soon.This is what i have collected so far. Edelbrock RPM Heads, Edelbrock RPM intake, Holly 770 street avenger carb, Carter mechanical fuel pump. The rear has a 323 gear and a 727 trans. Not sure on the Cam? The car will be used as a cruiser and maybe take it down the track on occasion. I would like to jump in the car, one pump on the gas and fire right up .

First.... throw away the 770 street avenger carb idea. Get a 750 double pumper, you will thank me. If you are dead set on it, I've got an 870 street avenger I would LOVE to sell you, because I only hang out with smart people around here, and none of them are crazy enough to trade for my mistake I made 7 years ago that's still in perfect condition.

To get back to your question.... highly doubtful
The cam is kind of what chooses whether you have a smooth idle, and getting a car to make good power means positioning the operating RPM of the cam in a place to make more power. Stock cars have smooth idles because the cams are positioned to make the best power from 2000-3000 RPM, hence they make great power there, and idle is close enough so that it doesn't behave erratically there.
Performance cams are meant for other ranges, and because horsepower is a function of torque, which means your best numbers will be after 5252 RPM, then picking a cam for 3000-5000 RPM operation range would be more suitable, which means your idle will not be smooth because it is outside of the camshafts operating range.

But, there is hope. Obviously because I have seen many cars that put down 500+ HP numbers with pretty smooth idles. How do they do it? Bigger cubes (stroke the 440), or forced induction, (supercharge or turbocharge it)

Too late on the carb. i already bought it. I don't think i need a double pumper for street use. I like the vaccum secondary and electric choke. The guy at the Performance shop that sold me the carb.said that Holley is all they use on their drag cars.

[mauve66]

Usually one needs to pump the gas at least once to seat the choke and fast idle.  Wonder if his carb was dumping raw gas out the venturies?

i should have clarified, he would come to the house and when we left it was still warm, never seen him start it bone cold at his house

[firefighter3931]

It really depends on what you consider "smooth" 

A mild street roller on a wide lobe center can make that number and still idle descent. 



Ron

[aifilaw]

It really depends on what you consider "smooth" 

A mild street roller on a wide lobe center can make that number and still idle descent. 



Ron

thumpity...thumpity...thumpity
as opposed to
RUMP!!!.....RUMP!!!.....RUMP!!!.....

[Mike DC]

         
8 liters flowing @ 4000 rpm = 4 liters flowing @ 8000 rpm. 

Same total amount of fuel being burned for power, two different ways of going about it.     





Step #1 --  Figure out how big the heads/cam/carb all need to be in order to flow the power you want. 

Step #2 --  The lower rpm (and more streetable) you want that power level to be reached at, the larger you need the motor's displacement to be underneath those mixture-flowing parts on top.


 

So build a mild stroker motor.  One decent notch bigger than stock heads/carb/cam + much more displacement underneath it = 500 hp at a moderate RPM with a smooth idle.

What you've basically done with this setup is just grow the overall size of the factory stock 440 magnum motor.  But you haven't totally changed the proportions of the cylinders/heads/carb/manifolds to each other, which is what monkeys with power curves & characteristics so much.  So the result of a mild stroker motor should produce a similar-shaped power curve to the stock motor that is just higher from start to finish.



The only major downside with this setup is that it'll burn more gas than the stock motor 100% of the time along with having more power 100% of the time.  And there will be torque strong enough to break stuff (if you consider that a downside).


       

[aifilaw]

I approve ^^^

[green69rt]

         
8 liters flowing @ 4000 rpm = 4 liters flowing @ 8000 rpm. 

Same total amount of fuel being burned for power, two different ways of going about it.     





Step #1 --  Figure out how big the heads/cam/carb all need to be in order to flow the power you want. 

Step #2 --  The lower rpm (and more streetable) you want that power level to be reached at, the larger you need the motor's displacement to be underneath those mixture-flowing parts on top.


 

So build a mild stroker motor.  One decent notch bigger than stock heads/carb/cam + much more displacement underneath it = 500 hp at a moderate RPM with a smooth idle.

What you've basically done with this setup is just grow the overall size of the factory stock 440 magnum motor.  But you haven't totally changed the proportions of the cylinders/heads/carb/manifolds to each other, which is what monkeys with power curves & characteristics so much.  So the result of a mild stroker motor should produce a similar-shaped power curve to the stock motor that is just higher from start to finish.



The only major downside with this setup is that it'll burn more gas than the stock motor 100% of the time along with having more power 100% of the time.  And there will be torque strong enough to break stuff (if you consider that a downside).


       

Yeah, stroke it.  440's are on of the best motors for stroking. Mild crank angles, low cylindar wear, big result for relatively modest cost!  There was an article in "Chrysler Engines Volume one" from 1995 that was an excellent article about engine design, yes it's old but still a lot of good info.  If you can't find it let me know and I'll try to send it to you.  (email me at boathobby@aol.com,  don't ask about the name!)

[Corellian Corvette]

I'm sure you can. My engine dyno'd at 470+ HP and 541+ TQ and I'm pulling 17hg of vacumm at idle at about 750RPM in idle (good idle quality/drivablity was my main concern)

That's on a 400 motor stroked to 470, but running a Edelbrock performer (stock replacement) intake and the HP iron exhaust manifolds. My builder thinks I could easily uncork another 30HP with headers and a more aggressive intake.

If you search my posts you can find my engine combo. Should be very easy to do.

[Chryco Psycho]

yes it can be done ,eaisly

[Brock Samson]

my 446 six-pack motor, (minus the six-pack topend) with mostly stock internal components was dynoed at 503 HP (before the addition of some other goodies) and it idles quite smoothly,...
here's a quick video clip... I'll be posting a new video soon, as tomarrow night i want to do a new longer one..
anyhow yes.

  http://www.youtube.com/watch?v=6N5xm-F_st8

and BTW:
i run a 770 street avenger on a weiland stealth manifold and i've never had a lick of trouble in nine years with that combo...
if i could change anything I'd only get a X pipe instead if the H pipe exhaust and i'd like to try the Magna flows as opposed to the Flowmasters i'm running,..
I'd listen to the fireman (ron) and chryo physco,.. as to their recommendations first, as they seem to have the most experiance.

[Rolling_Thunder]

stock magnum cam with a pro-charger   

[Purple440]

as a side note a friend of mine had a 440 6pak in a green 69 sweptline truck and he never had to pump the gas to start it, he'd just reach in through the window and turn the key, fired up everytime, i've never been able to get any of my carb cars to do that, and he thought it was funny that i couldn't

Aside from a cold start, I can reach in the window and turn the key and it fires right off every time.  The key in my case was matching the initial timing with my cam duration.  In talking with Ron, I learned that the more duration you have, the more initial timing it might need.  So for my cam: 230/230 @.050, I use 16 degrees initial timing.  Starts faster than my Maxima. 

- Doug